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VDD=3.3V vs. 3.0V?

The datasheet for the S64128M states that the typical VDD is 3.0V (+/-0.15V) but also specifies an absolute maximum of 3.6V. The datasheet for the controller itself, the ST7565R, specifies a maximum operating voltage of 3.3V with an absolute maximum of 3.6V. Everything else on our board is 3.3V. Are there any risks or other problems that could arise from running the S64128M VDD at 3.3V? Strictly speaking it's not out of spec, but it is higher than the typical spec. We'd like to avoid an additional regulator and level translator dedicated to the S64128M module. Thanks

Replies

Guest's picture
Guest
December 9, 2010

I agree, why?

I have used these displays in three designs, two using the smaller 32128. The first time I did not question the spec and used a 3.0 V supply and level translators. Subsequent designs I had no space to add this extra circuitry so I took a harder look and questioned these ratings.

The spec is very conservative and attempts to stay under the 3.3V max rating of the driver when powered with standard regulators with high tolerance. I decided to trust the driver specification but I did use a tight tolerance regulator just for the display. I used a Microchip TC-2185 3.3 +/- .4%. This regulator is essentially only 150 mV above the max. tolerance for the ST7565R but is well under any absolute maximum ratings. An additional regulator, no level translation required, and still a conservative design that I believe will be reliable.

dtechsupport's picture
dtechsupport
December 16, 2010

Correct, we are very conservative in our rating of 3.0V vs. 3.3V.